Common brand names:

Summary of Interactions with Vitamins, Herbs, & Foods

Replenish Depleted Nutrients

Tetracycline can interfere with the activity of folic acid, potassium, and vitamin B2, vitamin B6, vitamin B12, vitamin C, and vitamin K.1 This is generally not a problem when taking tetracycline for two weeks or less. People taking tetracycline for longer than two weeks should ask their doctor about vitamin and mineral supplementation. Taking 500 mg vitamin C simultaneously with tetracycline was shown to increase blood levels of tetracycline in one study.2 The importance of this interaction is unknown.

Taking large amounts of niacinamide, a form of vitamin B3, can suppress inflammation in the body. According to numerous preliminary reports, niacinamide, given in combination with tetracycline or minocycline, may be effective against bullous pemphigoid, a benign, autoimmune blistering disease of the skin.3, 4, 5, 6, 7, 8, 9 Preliminary evidence also suggests a similar beneficial interaction may exist between tetracycline and niacinamide in the treatment of dermatitis herpetiformis.10, 11

Tetracycline can interfere with the activity of folic acid, potassium, and vitamin B2, vitamin B6, vitamin B12, vitamin C, and vitamin K.12 This is generally not a problem when taking tetracycline for two weeks or less. People taking tetracycline for longer than two weeks should ask their doctor about vitamin and mineral supplementation. Taking 500 mg vitamin C simultaneously with tetracycline was shown to increase blood levels of tetracycline in one study.13 The importance of this interaction is unknown.

Taking large amounts of niacinamide, a form of vitamin B3, can suppress inflammation in the body. According to numerous preliminary reports, niacinamide, given in combination with tetracycline or minocycline, may be effective against bullous pemphigoid, a benign, autoimmune blistering disease of the skin.14, 15, 16, 17, 18, 19, 20 Preliminary evidence also suggests a similar beneficial interaction may exist between tetracycline and niacinamide in the treatment of dermatitis herpetiformis.21, 22

Tetracycline can interfere with the activity of folic acid, potassium, and vitamin B2, vitamin B6, vitamin B12, vitamin C, and vitamin K.25 This is generally not a problem when taking tetracycline for two weeks or less. People taking tetracycline for longer than two weeks should ask their doctor about vitamin and mineral supplementation. Taking 500 mg vitamin C simultaneously with tetracycline was shown to increase blood levels of tetracycline in one study.26 The importance of this interaction is unknown.

Several cases of excessive bleeding have been reported in people who take antibiotics.27, 28, 29, 30 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.31 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

Reduce Side Effects

A common side effect of antibiotics is diarrhea, which may be caused by the elimination of beneficial bacteria normally found in the colon. Controlled studies have shown that taking probiotic microorganisms—such as Lactobacillus casei, Lactobacillus acidophilus, Bifidobacterium longum, or Saccharomyces boulardii—helps prevent antibiotic-induced diarrhea.32

The diarrhea experienced by some people who take antibiotics also might be due to an overgrowth of the bacterium Clostridium difficile, which causes a disease known as pseudomembranous colitis. Controlled studies have shown that supplementation with harmless yeast—such as Saccharomyces boulardii33 or Saccharomyces cerevisiae (baker’s or brewer’s yeast)34—helps prevent recurrence of this infection.

Treatment with antibiotics also commonly leads to an overgrowth of yeast (Candida albicans) in the vagina (candida vaginitis) and the intestines (sometimes referred to as “dysbiosis”). Controlled studies have shown that Lactobacillus acidophilus might prevent candida vaginitis.35

Tooth discoloration is a side effect of minocycline observed primarily in young children, but it may occur in adults as well. Vitamin C supplementation may prevent staining in adults taking minocycline.36

Support Medicine

When taken with amoxicillin, bromelain was shown to increase absorption of amoxicillin in humans.41 When 80 mg of bromelain was taken together with amoxicillin and tetracycline, blood levels of both drugs increased, though how bromelain acts on drug metabolism remains unknown.42 An older report found bromelain also increased the actions of other antibiotics, including penicillin, chloramphenicol, and erythromycin, in treating a variety of infections. In that trial, 22 out of 23 people who had previously not responded to these antibiotics did so after adding bromelain taken four times per day.43

Doctors will sometimes prescribe enough bromelain to equal 2,400 gelatin dissolving units (listed as GDU on labels) per day. This amount would equal approximately 3,600 MCU (milk clotting units), another common measure of bromelain activity.

Reduces Effectiveness

A recent study showed that taking calcium carbonate and gemifloxacin at the same time results in a significant reduction in blood levels of the drug.46 Consequently, gemifloxacin and calcium supplements should not be taken at the same time.

Minerals such as aluminum, calcium, copper, iron, magnesium, manganese, and zinc can bind to ciprofloxacin, greatly reducing the absorption of the drug.47, 48, 49, 50 Because of the mineral content, people are advised to take ciprofloxacin two hours after consuming dairy products (milk, cheese, yogurt, ice cream, and others), antacids (Maalox®, Mylanta®, Tums®, Rolaids®, and others), and mineral-containing supplements.51

Preliminary research in animals has shown that fennel (Foeniculum vulgare) may reduce the absorption of ciprofloxacin.52 This interaction may be due to the rich mineral content of the herb; it has not yet been reported in humans. People taking ciprofloxacin should avoid supplementing with fennel-containing products until more is known.

A review of interactions involving quinolone antibiotics indicated that supplements containing iron, when taken at the same time as gemifloxacin, might reduce absorption of the drug up to 50%.53 Consequently, gemifloxacin and supplements containing iron should not be taken at the same time.

Khat

Khat (Catha edulis) is an herb found in East Africa and Yemen that has recently been imported into the United States. Studies have shown that chewing khat significantly reduces the absorption of ampicillin,54 which might reduce the effectiveness of the antibiotic. Therefore, people taking ampicillin should avoid herbal products that contain khat.

One study showed that taking an antacid containing magnesium and aluminum ten minutes before gemifloxacin results in an 85% reduction in the absorption of the drug.55 Consequently, gemifloxacin and supplements containing magnesium should not be taken at the same time.

Minerals such as aluminum, calcium, copper, iron, magnesium, manganese, and zinc can bind to ciprofloxacin, greatly reducing the absorption of the drug.56, 57, 58, 59 Because of the mineral content, people are advised to take ciprofloxacin two hours after consuming dairy products (milk, cheese, yogurt, ice cream, and others), antacids (Maalox®, Mylanta®, Tums®, Rolaids®, and others), and mineral-containing supplements.60

Minerals including calcium, iron, magnesium, and zinc can bind to fluoroquinolones, including ofloxacin, greatly reducing drug absorption.61 Ofloxacin should be taken four hours before or two hours after consuming antacids (Maalox®, Mylanta®, Tumms®, Rolaids® and others) that may contain these minerals and mineral-containing supplements.62

Potential Negative Interaction

none

Explanation Required

Berberine is a chemical extracted from goldenseal(Hydrastis canadensis),barberry(Berberis vulgaris), and Oregon grape(Berberis aquifolium), which has antibacterial activity. However, one double-blind study found that 100 mg berberine given with tetracycline (a drug closely related to doxycycline) reduced the efficacy of tetracycline in people with cholera.65 In that trial, berberine may have decreased tetracycline absorption. Another double-blind trial found that berberine neither improved nor interfered with tetracycline effectiveness in cholera patients.66 Therefore, it remains unclear whether a significant interaction between berberine-containing herbs and doxycycline and related drugs exists.

Several cases of excessive bleeding have been reported in people who take antibiotics.67, 68, 69, 70 This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.71 Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.

Please read the disclaimer about the limitations of the information provided here. Do NOT rely solely on the information in this article. The Healthnotes knowledgebase does not contain every possible interaction.

The information presented by Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over-the-counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2017.

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